Chen Binqing, Dang Xie, Bai Wenting, Liu Min, Li Ying, Zhu Lilan, Yang Yanqiu, Yu Peihang, Ren Huibo, Huang Dingquan, Pan Xue, Wang Haifeng, Qin Yuan, Feng Shiliang, Wang Qin, Lin Deshu
Basic Forestry and Proteomic Research Center, Fujian Provincial Key Laboratory of Plant Functional Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, 712100, China.
New Phytol. 2022 Nov;236(4):1310-1325. doi: 10.1111/nph.18433. Epub 2022 Sep 1.
Plant cells continuously experience mechanical stress resulting from the cell wall that bears internal turgor pressure. Cortical microtubules align with the predicted maximal tensile stress direction to guide cellulose biosynthesis and therefore results in cell wall reinforcement. We have previously identified Increased Petal Growth Anisotropy (IPGA1) as a putative microtubule-associated protein in Arabidopsis, but the function of IPGA1 remains unclear. Here, using the Arabidopsis cotyledon pavement cell as a model, we demonstrated that IPGA1 forms protein granules and interacts with ANGUSTIFOLIA (AN) to cooperatively regulate microtubule organisation in response to stress. Application of mechanical perturbations, such as cell ablation, led to microtubule reorganisation into aligned arrays in wild-type cells. This microtubule response to stress was enhanced in the IPGA1 loss-of-function mutant. Mechanical perturbations promoted the formation of IPGA1 granules on microtubules. We further showed that IPGA1 physically interacted with AN both in vitro and on microtubules. The ipga1 mutant alleles exhibited reduced interdigitated growth of pavement cells, with smooth shape. IPGA1 and AN had a genetic interaction in regulating pavement cell shape. Furthermore, IPGA1 genetically and physically interacted with the microtubule-severing enzyme KATANIN. We propose that the IPGA1-AN module regulates microtubule organisation and pavement cell shape.
植物细胞不断经历由承受内部膨压的细胞壁所产生的机械应力。皮层微管与预测的最大拉伸应力方向对齐，以引导纤维素生物合成，从而导致细胞壁强化。我们之前已鉴定出拟南芥中一种假定的微管相关蛋白——花瓣生长各向异性增加蛋白1（IPGA1），但其功能仍不清楚。在这里，我们以拟南芥子叶的铺板细胞为模型，证明IPGA1形成蛋白颗粒，并与窄叶蛋白（AN）相互作用，以协同调节微管组织对应激的反应。施加机械扰动，如细胞消融，会导致野生型细胞中的微管重新组织成排列整齐的阵列。在IPGA1功能缺失突变体中，这种微管对应激的反应增强。机械扰动促进了IPGA1颗粒在微管上的形成。我们进一步表明，IPGA1在体外和微管上均与AN发生物理相互作用。ipga1突变等位基因表现出铺板细胞指状交叉生长减少，形状光滑。IPGA1和AN在调节铺板细胞形状方面存在遗传相互作用。此外，IPGA1在遗传和物理上均与微管切割酶katanin相互作用。我们提出，IPGA1-AN模块调节微管组织和铺板细胞形状。
